FabDigit

YAG vs N-BK7 and 2 more: properties

YAGN-BK7Fused SilicaSapphire

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

300 GPa43.5 Msi
82 GPa11.9 Msi
72 GPa10.4 Msi
400 GPa58 Msi

Shear Modulus

115 GPa16.7 Msi
34 GPa4.9 Msi
31 GPa4.5 Msi
148 GPa21.5 Msi

Bulk Modulus

185 GPa26.8 Msi
47 GPa6.7 Msi
37 GPa5.4 Msi
250 GPa36.3 Msi

Poisson's Ratio

0.25
0.21
0.17
0.27

Tensile Strength (Ultimate)

180 MPa26.1 ksi
50 MPa7.3 ksi
50 MPa7.3 ksi
400 MPa58 ksi

Compressive Strength

1,300 MPa189 ksi
1,000 MPa145 ksi
1,150 MPa167 ksi
2,000 MPa290 ksi

Flexural Strength

280 MPa40.6 ksi
65 MPa9.4 ksi
67 MPa9.7 ksi
760 MPa110 ksi

Fracture Toughness (K_IC)

1.6 MPa·√m1.5 ksi·√in
0.85 MPa·√m0.77 ksi·√in
0.75 MPa·√m0.68 ksi·√in
2.2 MPa·√m2 ksi·√in

Hardness, Vickers

1,350 HV
610 HV
700 HV
2,000 HV

Hardness, Knoop

1,215 HK
610 HK
560 HK
2,000 HK

Hardness, Mohs

8.3
6
6
9

Shear Strength

40 MPa5.8 ksi
30 MPa4.4 ksi
350 MPa50.8 ksi

Same in both: Elongation at Break 0%

Physical

Density and transition temperatures.

Density

4.55 g/cm³0.16 lb/in³
2.51 g/cm³0.09 lb/in³
2.2 g/cm³0.08 lb/in³
3.98 g/cm³0.14 lb/in³

Melting Point (Solidus)

1,940°C3,524 °F
1,713°C3,115 °F
2,053°C3,727 °F

Refractive Index

1.82
1.517
1.459
1.768

Light Transmission

84%
92%
92%
85%

Same in both: Porosity 0%

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

11.2 W/m·K6.5 BTU/hr·ft·°F
1.1 W/m·K0.64 BTU/hr·ft·°F
1.4 W/m·K0.8 BTU/hr·ft·°F
27 W/m·K15.6 BTU/hr·ft·°F

Specific Heat Capacity

600 J/kg·K0.14 BTU/lb·°F
858 J/kg·K0.2 BTU/lb·°F
740 J/kg·K0.18 BTU/lb·°F
761 J/kg·K0.18 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

7.8 µm/m·K4.3 µin/in·°F
7.1 µm/m·K3.9 µin/in·°F
0.55 µm/m·K0.31 µin/in·°F
5.8 µm/m·K3.2 µin/in·°F

Max Service Temperature (continuous)

1,600°C2,912 °F
500°C932 °F
1,100°C2,012 °F
1,800°C3,272 °F

Min Service Temperature

-269°C-452 °F
-200°C-328 °F
-200°C-328 °F
-269°C-452 °F

Electrical

Conductivity and insulation.

Electrical Resistivity

1×10¹² Ω·m3.94×10¹⁹ µΩ·in
1×10¹² Ω·m3.94×10¹⁹ µΩ·in
1×10¹⁶ Ω·m3.94×10²³ µΩ·in
1×10¹⁴ Ω·m3.94×10²¹ µΩ·in

Dielectric Constant (1 MHz)

11.7
7
3.8
9.8

Volume Resistivity

1×10¹⁴ Ω·cm
1×10¹⁴ Ω·cm
1×10¹⁸ Ω·cm
1×10¹⁶ Ω·cm

Dielectric Strength

15 kV/mm381 V/mil
30 kV/mm762 V/mil
17 kV/mm432 V/mil

Dissipation Factor (1 MHz)

1×10⁻⁴
1×10⁻⁴

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

92 / 100
78 / 100
95 / 100
95 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

5 / 100
18 / 100
10 / 100
5 / 100

Polishability

95 / 100
95 / 100
98 / 100
98 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

2,000 MJ/kg859,846 BTU/lb
30 MJ/kg12,898 BTU/lb
55 MJ/kg23,646 BTU/lb
400 MJ/kg171,969 BTU/lb

Embodied Carbon (primary production)

150 kg CO₂/kg
2 kg CO₂/kg
4 kg CO₂/kg
60 kg CO₂/kg

Typical Recycled Content

10%
5%
0%
5%

Embodied Water

90 L/kg10.8 gal/lb
80 L/kg9.6 gal/lb
250 L/kg30 gal/lb

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

40 kN·m/kg
20 kN·m/kg
23 kN·m/kg
101 kN·m/kg

Specific Stiffness (E / density)

65.9 MN·m/kg
32.7 MN·m/kg
32.7 MN·m/kg
100.5 MN·m/kg

Thermal Diffusivity

4.1 mm²/s
0.5 mm²/s
0.8 mm²/s
8.9 mm²/s

Thermal Shock Resistance Index

1
0
2
5

Strength versus weight

Yield strength against density for every glass grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

501002005002.533.5Density (g/cm³)Yield strength (MPa) — log scaleN-BK7Fused SilicaSapphire

Manufacturing and finishing

CapabilityYAGN-BK7Fused SilicaSapphire
Default conditionAnnealed GlassAnnealed GlassAnnealed Glass
Relative cost$$$$ High$$ Standard$$ Standard$$ Standard
Min. machined wall
Best machined surface

Ready to make it?

Upload a CAD file and FabDigit prices the part in YAG and N-BK7 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.

Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.